J Llibre – författare

This volume is an outgrowth of the Third International Symposium on Hamiltonian Systems and Celestial Mechanics. The main topics are Arnold diffusion, central configurations, singularities in few-body problems, billiards, area-preserving maps, and geometrical mechanics. All papers in the volume went through the refereeing process typical of a mathematical research journal.

The main theme of the ECIT conferences is Iteration Theory, on the borderline between Dynamics and Functional Equations. The aim is to foster symbiosis between mainstream dynamics and iteration theory treated in the style of functional equations theory. The following topics are focused: turbulence and iteration, characterization of chaos, kneading theory, symbolic dynamics, bifurcation, periods of maps, topological dynamics, discrete retarded dynamical systems, cellular automata as dynamical systems, iterative roots of formal power series, iterative roots of polynomials, phantom iterative roots, iterative groups and semigroups, families of commuting functions, algebraic aspects of iteration theory and functional equations.

This volume puts together several important lectures on the Hamiltonian Systems and Celestial Mechanics to form a comprehensive and authoritative collection of works on the subject. The papers presented in this volume are an outgrowth of the lectures that took place during the "International Symposium on Hamiltonian Systems and Celestial Mechanics", which was held at the CIMAT (Centro de Investigacion en Matematicas, Guanajuato, Mexico) from September 30 to October 4, 1991. In general, the lectures explored the subject of the Hamiltonian Dynamics and Celestial Mechanics and emphasized its relationship with several aspects of topology, mechanics and dynamical systems.

It is well known that the restricted three-body problem has triangular equilibrium points. These points are linearly stable for values of the mass parameter, μ, below Routh's critical value, μ1. It is also known that in the spatial case they are nonlinearly stable, not for all the initial conditions in a neighborhood of the equilibrium points L4, L5 but for a set of relatively large measures. This follows from the celebrated Kolmogorov–Arnold–Moser theorem. In fact there are neighborhoods of computable size for which one obtains “practical stability” in the sense that the massless particle remains close to the equilibrium point for a big time interval (some millions of years, for example).According to the literature, what has been done in the problem follows two approaches: (a) numerical simulations of more or less accurate models of the real solar system; (b) study of periodic or quasi-periodic orbits of some much simpler problem.The concrete questions that are studied in this volume are: (a) Is there some orbit of the real solar system which looks like the periodic orbits of the second approach? (That is, are there orbits performing revolutions around L4 covering eventually a thick strip? Furthermore, it would be good if those orbits turn out to be quasi-periodic. However, there is no guarantee that such orbits exist or will be quasi-periodic). (b) If the orbit of (a) exists and two particles (spacecraft) are put close to it, how do the mutual distance and orientation change with time?As a final conclusion of the work, there is evidence that orbits moving in a somewhat big annulus around L4 and L5 exist, that these orbits have small components out of the plane of the Earth–Moon system, and that they are at most mildly unstable.

In this book the problem of station keeping is studied for orbits near libration points in the solar system. The main focus is on orbits near halo ones in the (Earth+Moon)–Sun system. Taking as starting point the restricted three-body problem, the motion in the full solar system is considered as a perturbation of this simplified model. All the study is done with enough generality to allow easy application to other primary-secondary systems as a simple extension of the analytical and numerical computations.